The present invention relates to inkjet printheads. In particular, it relates to a thin film configuration of a heater chip of the printhead optimized to attain a particular energy range for stable ink jetting performance.
The art of printing images with inkjet technology is relatively well known. In general, an image is produced by emitting ink drops from an inkjet printhead at precise moments such that they impact a print medium, such as a sheet of paper, at a desired location. The printhead is supported by a movable print carriage within a device, such as an inkjet printer, and is caused to reciprocate relative to an advancing print medium and emit ink drops at such times pursuant to commands of a microprocessor or other controller. The timing of the ink drop emissions corresponds to a pattern of pixels of the image being printed. Other than printers, familiar devices incorporating inkjet technology include fax machines, all-in-ones, photo printers, and graphics plotters, to name a few.
A conventional thermal inkjet printhead includes access to a local or remote supply of color or mono ink, a heater chip, a nozzle or orifice plate attached to the heater chip, and an input/output connector, such as a tape automated bond (TAB) circuit, for electrically connecting the heater chip to the printer during use. The heater chip, in turn, typically includes a plurality of thin film resistors or heaters fabricated by deposition, masking and etching techniques on a substrate such as silicon.
To print or emit a single drop of ink, an individual heater is uniquely addressed with a small amount of current to rapidly heat a small volume of ink. This causes the ink to vaporize in a local ink chamber (between the heater and nozzle plate) and be ejected through and projected by the nozzle plate towards the print medium.
As demands for higher resolution and increased printing speed continue, however, heater chips are made smaller with more and denser heater configurations. Thus, heater chip size, fragility, life, and heat dissipation becomes implicated with all future designs. In addition, printheads accrue fewer costs when heater chips use as little energy as possible when firing each heater.
Accordingly, the inkjet printhead arts desire optimum heater configurations requiring little firing energy that support relatively long life, small size, high density, chip stability and good heat dissipation properties.
The above-mentioned and other problems become solved by applying the apparatus and method principles and teachings associated with the hereinafter described heater chip configuration for an inkjet printhead and printer.
In one embodiment, the heater chip includes a heater having a length, width and thickness. The length multiplied by the width (heater area) is in a range from about 50 to about 500 micrometers squared while the thickness is in a range from about 500 to about 5000 or 6000 angstroms. In another embodiment, the heater area is less than about 400 micrometers squared while the thickness is less than about 4000 angstroms. The heater chip is formed as a plurality of thin film layers on a substrate. In particular, a thermal barrier layer is on the substrate, a resistor layer is on the thermal barrier layer, a conductor layer is on the resistor layer and an overcoat layer is on the resistor layer. The overcoat layer may include both a passivation and a cavitation layer. The conductor layer includes an anode and a cathode.
In other embodiments, the energy required to jet or emit a single drop of ink from the heater during use is in a range from about 0.007 to about 0.99 or about 1.19 microjoules. Energy ranges for heater chips are disclosed in tabular form for all heaters having an area ranging from about 50 to about 4000 micrometers squared and for thicknesses ranging from about 500 to about 16,000 angstroms.
Printheads containing the heater chip and printers containing the printheads are also taught.
These and other embodiments, aspects, advantages, and features of the present invention will be set forth in the description which follows, and in part will become apparent to those of ordinary skill in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims.